KR19980702167A - Passenger restraint system powered by gas generating composition - Google Patents

Abstract

(i) nitroguanidine; (ii) oxidizing agents; (iii) A passenger restraint system is disclosed comprising a gas generating composition comprising silicon or aluminum oxide, a mixed oxide of silicon and aluminum, or a silicate. The system may include an air bag or seat belt pretensioner.

Description

Passenger restraint system powered by gas generating composition

Passenger restraint systems are now widely used. Typical systems are inflatable airbags and seat belt pretensioners. In both cases there is a need for a composition that can rapidly generate gas upon impact. In the case of an air bag the composition must inflate the bag and in the case of a seat belt pretensioner it must provide the driving force to activate the pretension mechanism. Such compositions are generally combustible and are burned by means of an igniter initiated electrically or mechanically.

Various gaseous compositions have been proposed so far and mention may be made of sodium azide based compositions, single or dual based propellant compositions, aminotetrazole based compositions. In fact, however, none of these compositions is completely satisfactory.

Sodium azide based composition only generates 50% by weight of nitrogen gas; The remaining 50% by weight is a particulate solid product which, for example, does not contribute to airbag inflation and must be filtered from the hot gas stream. Sodium azide itself is very toxic, expensive to manufacture and difficult to process. However, it is widely used because the generated propellant gas is mainly nitrogen and low toxicity.

Single and double base propellants have a limited useful life when stored at high temperatures. Therefore, there has been a growing interest in the use of propellants containing nitrocellulose in airbags installed in vehicles driven in hot climates, such as in deserts in the United States and Australia. Because these propellants cannot provide a 15-year service life. In addition, carbon monoxide accounts for 33% of the weight of combustion products, and this gas is highly toxic. However, the single and double base propellants have the claim that at least 99.5% by weight is converted to gas, thus eliminating the need for equipment to filter solid products.

Compositions based on aminotetrazol and derivatives thereof (eg, 5-aminotetrazol) are superior to single and double basal propellants in stability and sodium azide in toxicity. The conversion to gas is about 60 to 70% by weight, most of which is nitrogen and little carbon monoxide. But up to 10% is carbon dioxide. Such compositions generate a smaller proportion of particulate solid combustion products than sodium azide compositions but produce more solid products than single or dual base propellants. However, the cost of preparing aminotetrazole is very high and its advantages are not sufficient to overcome this aspect.

From the above description, there is a need for a low toxic gas generating composition that has a high weight ratio converted to gas upon combustion, can be manufactured, handled and processed at elevated temperatures for a long time and is relatively inexpensive, and generates low combustion products. Becomes obvious.

Summary of the Invention

According to the present invention there is provided a nitroguanidine-containing stable gas generating composition for use in a passenger restraint system.

The present invention provides a passenger restraint system comprising a gas generating composition consisting of:

(i) nitroguanidine;

(ii) oxidizing agents;

(iii) silicon oxide or aluminum oxide, hybrid oxides of silicon and aluminum, or silicates.

The nitroguanidine component (i) of the composition of the present invention is commercially available as Picrite or NQ. The nitroguanidine component is used as an alpha form containing long, thin and crystalline needles. Of course, this component is relatively low toxicity and can be produced inexpensively.

The oxidant component (ii) used in the compositions of the present invention is also low in toxicity and generates low toxicity combustion products. Suitable oxidizing agents are nitrates, in particular nitrates of metals, in particular nitrates of alkali and alkaline earth metals, in particular sodium, potassium and strontium nitrates.

Other oxidants, such as potassium perchlorate, can be used alone or in combination with metal nitrates.

Oxidizing agents, including bismuth, barium, vanadium and chromium salts, are not preferred because of the toxicity of these compounds themselves or their combustion products.

Component (iii) of the composition comprises an oxide of silicon or aluminum, a mixed oxide of silicon and aluminum, or a silicate. Among them, it is preferred to react with the oxide generated by the combustion of the oxidant component to form silicates, aluminates, or hybrid compounds thereof. Suitable compounds for the third component are silica, alumina, silicoaluminates, diatomaceous earth solids and silicate containing minerals. The third component is in the finely divided state.

The composition of the present invention consists of 50 to 67% by weight of nitroguanidine, 30 to 45% by weight of oxidant, and 3 to 5% by weight of silicone and / or aluminum containing compound.

The composition of the present invention is relatively non-toxic and at least 78% by weight is converted to gas and less than 0.02% of the gas is carbon monoxide. Preferred compositions are stable, for example, at elevated temperatures up to 200 ° C.

The passenger restraint system according to the invention is a vehicle safety airbag or seat belt pretension.

The present invention relates to a passenger restraint system powered by a gas generating composition.

1 shows a side view of an embodiment of a passenger restraint system according to the invention in the form of a seat belt pretensioner propulsion device;

FIG. 2 is a plan view of the pretensioner of FIG. 1. FIG.

3 is an enlarged side view of the pretensioner of FIGS. 1 and 2 with part cut away to show the mode of operation;

4 is an end front view of the pretensioner of FIGS. 1-3 with a portion cut away to show the mode of operation;

5 is a cross-sectional view of the gas generator of the pretensioner shown in FIGS.

6 shows another embodiment of a passenger restraint system according to the invention in the form of an inflator assembly for an air bag.

* Code Description

1 ... pretensioner 2 ... curved pressure line

3 ... drive wheel 4 ... shaft

5.Gas generator 6 ... dotted line

7 ... opened side channel 8 ... inhibiting member

9 ... chamber 10 ... panel

11 metal ball 12 recessed part

13 Combustion gas generating composition

15 ... end 16 ... felt plug

17 ... Foam 21 ... Expander Assembly

22.Housing 23 ... Flange

Composition pellets 25

26 ... wires 27, 28 ... clamping surface

29.Cap member 30 ... Filter

In FIG. 1 the pretensioner 1 comprises a curved pressure tube 2 wound around a drive wheel 3 attached to a shaft 4. The pressure tube 2 is mounted eccentrically about the axis of the drive wheel 3 and has a slightly larger curvature diameter than the wheel. The tube 2 has a closed end with a cap enclosing the gas generator 5, the open end of which is shown by a dashed line 6 and forms an open side channel 7. At the end of the channel 7 there is a restraining member 8. As shown in FIG. 2, the curved pressure tube 2 makes about 1½ revolutions around the drive wheel 3. The pretensioner is in a collection chamber 9 which may include some or all of the seat belt retractor housings and the chamber 9 has a transparent panel 10 for viewing therein.

In FIG. 3 showing the pre-tensioner in operation, it is shown that a row of metal balls 11 passes along the channel 7 of the pressure tube 2. There are 30 to 50 such balls 11 in the pressure pipe 2. The ball 11 has a diameter slightly smaller than the inner diameter of the tube 2 and can move freely in the tube. Around the drive wheel 3 there is a series of recesses 12 which are spaced apart so that the surface of the balls abuts when adjacent balls 11 are located in the recesses. This arrangement is also shown in FIG. 4 showing the drive shaft 4 attached to the reel of the seat belt retractor (not shown).

5 shows the gas generating apparatus 5 in detail. The combustion gas generating composition 13 (composition 1 of the embodiment) according to the present invention is filled into an internal pressure plug 14 firmly mounted to the end 15 of the pressure tube 2. The combustion composition 13 is burned by an electronic igniter (not shown) activated by a deceleration sensor (not shown). A felt plug 16 is located at the end 15 of the pressure tube 2 and acts as a limiting member against the movement of the balls 11 in a row.

In the stop or inactive position of the pre-tensioner the ball 11 is injected into the pressure tube 2 after the ball is inserted and by the rigid foam 17 which solidifies to hold the ball 11 in the pressure tube 2. It is limited within. The plug 16 prevents the foam from reacting with the combustion composition. Using the ball 11 held in the tube 2 the drive wheel 3 and the shaft 4 can freely rotate with the reel of the seat belt retractor. The ball retaining means may comprise a brittle plug or spring means which are compressed when the ball is released from the pressure tube.

In an impending collision, the deceleration sensor activates the electronic igniter to explode the combustion gas generating composition 13. The volume of gas generated by the composition 13 is sufficient to displace the felt plug 16 and to propel the row of balls 11 at a significant speed along the pressure tube 2. When the ball reaches the open channel 7 it contacts the recess on the drive wheel 3 to rotate the drive wheel 3 and the drive shaft 4 at high speed. The drive shaft rotates the reel of the seat belt retractor, causing the seat belt to retract to the required extent.

The path of the ball is tangential with respect to the circumference of the drive wheel 3 and comes into contact with the restraining member 8 at the end of the open channel 7 as the ball moves and is significantly decelerated. This prevents the ball from damaging the walls of the collection chamber 9. The pretensioner is located within the seat belt retractor housing including the collection chamber 9 and can be observed through the transparent panel 10 to visually recognize whether the pretensioner is activated when the ball is released from the open channel 7. Can be collected at the bottom of the housing. The spent ball can be recovered and reused with fresh filling of the appropriate combustion composition.

The force acting on the drive wheel after the final ball leaves the circumference of the drive wheel 3 is no longer present and is subsequently locked in place by the seat belt systolic lock. When the vehicle is stopped, the seat belt systolic lock is released and the seat belt can be used again as normal.

Another embodiment of a passenger restraint system according to the invention is shown in FIG. 6, which shows an inflator assembly for an airbag.

The inflator assembly 21 generally comprises a cylindrical housing 22 having an integral peripheral flange 23. The flange 23 has a means (not shown) for attaching to an automobile dashboard, handle or handle column. The composition pellets 24 are filled in the housing 22 and the igniter 25 is sealed in the housing 22. Wire 26 is connected to igniter 25. The flange 23 returns to provide first and second gripping surfaces 27 and 28 where the edge (not shown) of the airbag mount is gripped. The airbag has been omitted for clarity but is folded and gripped by the flange for a hermetic seal with the inflator assembly.

On the housing 22 is mounted a cap member 29 provided with a skirt-shaped particle annular filter 30. The filter 30 and the cap member 29 are firmly fixed to the housing 22 and are located at the air bag inlet during operation.

Wires are connected to an electrical control (not shown) that electrically activates the igniter 25 when a rapid deceleration is detected in operation. The igniter 25 burns the pellets of composition 1 which quickly generate a large amount of gas. The gas enters the airbag through particle filter 30 and causes rapid expansion.

The invention is not limited to the details of the foregoing embodiments but extends to the combination of novel features disclosed herein (including claims, summaries, and drawings) and to the combination of steps of the disclosed method.

A gas generating solid composition according to the invention is prepared by mixing 58.1 wt% nitroguanidine, 37.9 wt% sodium nitrate particles, and 4 wt% silica in a mixer (composition 1). The composition is stable at 105 ° C. for 6 months.

Computer modeling experiments predict that the properties of composition 1 are as follows when burned:

Gas Generation Rate: 29.8 mol / gram

Solid product weight ratio: 21.5%

Conversion rate to gas: 78.5%

Density: 1.9g / cc

Computer modeling experiments predict that the gaseous combustion product (molar ratio) of composition 1 is:

Carbon Monoxide: 0.00025

CO2: 0.15446

Hydrogen: 0.00024

Water vapor: 0.35794

Nitrogen: 0.43337

Claims (14)

(i) nitroguanidine; (ii) oxidizing agents; (iii) A passenger restraint system comprising an oxide of silicon or aluminum, a mixed oxide of silicon and aluminum, or a gaseous composition of silicates. The system of claim 1 wherein the oxidant comprises a metal nitrate. The system of claim 1 or 2, wherein the oxidant comprises alkali metal nitrate. The system of claim 1, wherein component (iii) comprises silica. The system of claim 1, wherein component (iii) is present in a finely divided state. The composition of claim 1, wherein the gas generating composition comprises from 50 to 67 weight percent nitroguanidine, based on the total weight of the composition; 30 to 45 weight percent oxidizing agent; 3 to 5 weight percent of a silicon or aluminum containing compound. The system of claim 1, wherein the gas generating composition comprises nitroguanidine, sodium nitrate, and silica. The system of claim 1, comprising the gas generating composition described in the examples. A passenger restraint system comprising the gas generating composition described in the specification. 10. The system of claim 9, comprising the gas generating composition according to any one of claims 1-9. The system of claim 9 or 10, wherein the gas generating composition is contained within an inflator assembly connected to the airbag to be inflated by the gas generating composition. Passenger suppression system described in the specification. A passenger restraint system in which an airbag is inflated, including an airbag and a gas generating combustion composition including nitroguanidine. A passenger restraint system comprising an inflator assembly for an airbag comprising a gas generating composition comprising nitroguanidine.